This invention relates to a method and apparatus for use in the production of books.
U.K. patent specification No. GB-A-1473502 describes a book production method which is a continuous process from the operation of the printing press through compilation of a batch of signatures ready for binding together to form one or more books. In the system described in that specification, the batches of signatures are printed "two-up", in a "come and go" format. That is, in the example described in that specification, each batch of signatures can be considered as having two distinct halves, each half having half the number of pages required to make up the book. Two such batches are then placed together face to face, one batch having been rotated through 180.degree. with respect to the other. This pair of batches of signatures is then bound, and sawn in half to produce two identical complete books. The advantage of such a two-up, come and go process is that since the bindery is binding two books at a time, its output is doubled, while at the same time the printing cylinders of the press do not need to have expensive duplicate plates for each page of the book, and are easy and quick to set up. Traditionally, such two-up, come and go processes involved manual rotation of batches of signatures or of individual signatures before the signatures are bound, and specification No. GB-A-1473502 is directed to automating that process.
In such a machine, it is nevertheless economic to have duplicate printing plates for each page of the book and to print "straight" rather than "come and go", if the number of pages in the particular book being printed is less than half the capacity of the press. Clearly, it is then no longer necessary to rotate half the batches of signatures through 180.degree..
A problem arises, however, if it is desired to print a relatively large book having more pages than the capacity of the press. On the above prior art system, the only way of printing such books with many pages would be to install a press having a sufficiently large capacity. Of course, such a large capacity press would be more expensive, and would be uneconomic because most books do not have a large number of pages and so the large capacity of the press would be underused for perhaps 90% of print runs.
It is therefore desirable to have a system which can produce such books with a large number of pages. At the same time, it is desirable to have a system which is sufficiently flexible to remain economic for print runs with a smaller number of pages.